[求助]gwd-17-32

totolin116

32。Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.

 

A.        a reasonably clear picture has emerged of the patterns and causes of ocean currents

B.        a reasonably clear picture of the patterns of ocean currents and their causes have emerged

C.       a reasonably clear picture emerged of ocean currents, their patterns and the causes of them

D.       there have emerged a reasonably clear picture of the patterns of ocean currents and what caused them

E.        there had emerged a reasonably clear picture of the patterns of ocean currents and their causes

答案是a.1）不明白为什么a要用has emerged这个时态，想了很久实在无办法理解。

              2）不知道c有什么错

             劳烦各位赐教~~！！

eddienumb

c的错除了时态  their patterns and the causes of them   这是叫双重主格么？我不清清楚这种语法错误叫什么名字  但肯定是错的 
 关于事态  in/during/within/over  + last/past /recent + 一个时间   应该用现在完成时 

nettrinity

不懂，顶一下

aeoluseros

以下是引用eddienumb在2006-10-13 1:06:00的发言：
c的错除了时态  their patterns and the causes of them   这是叫双重主格么？我不清清楚这种语法错误叫什么名字  但肯定是错的  

um...求解...这个是什么错误呢？